改善既有的代码-重构.ppt

1、重构技术,邱百超 badqiu(a),讲解内容,重构介绍 重构原则 代码的坏味道 重构技巧 重构工具使用实例 Q if( name != null if( age != null if( !isNullOrEmpty( name ) ) . String age = request.getParameter(Age); if( !isNullOrEmpty( age ) ) . private boolean isNullOrEmpty( final String string ) if( string != null ,Extract Methods(提炼函数：清除注释）,void prin

2、tOwing() /print banner System.out.println(“*”); System.out.println(“Banner”); System.out.println(“*”); /print details System.out.println (name: + _name); System.out.println (amount + getOutstanding(); ,void printOwing() printBanner(); printDetails(getOutstanding(); void printBanner() System.out.prin

3、tln(“*”); System.out.println(“Banner”); System.out.println(“*”); void printDetails (double outstanding) System.out.println (name: + _name); System.out.println (amount + outstanding); ,Inline Method(将函数内联化),Inline Temp（将临时变量内联化）,Replace Temp with Query（以查询取代临时变量）,double basePrice = _quantity * _itemP

4、rice; if (basePrice 1000) return basePrice * 0.95; else return basePrice * 0.98;,if (basePrice() 1000) return basePrice() * 0.95; else return basePrice() * 0.98; . double basePrice() return _quantity * _itemPrice; ,Introduce Explaining Variable（引入解释性变量）,boolean isMacOs = platform.toUpperCase().index

5、Of(MAC) -1; boolean isIEBrowser = browser.toUpperCase().indexOf(IE) -1; boolean wasResized = resize 0; if (isMacOs System.out.println (temp); temp = _height * _width; System.out.println (temp);,double perimeter = 2 * (_height + _width); System.out.println (perimeter); double area = _height * _width;

6、 System.out.println (area);,Remove Assignments to Parameters（移除对参数的赋值）,Replace Method with Method Object（以函数对象取代函数）,Substitute Algorithm（替换算法）,Replace Nested Conditional with Guard Clauses,double getPayAmount() double result; if (_isDead) result = deadAmount(); else if (_isSeparated) result = separa

7、tedAmount(); else if (_isRetired) result = retiredAmount(); else result = normalPayAmount(); ; return result; ;,double getPayAmount() if (_isDead) return deadAmount(); if (_isSeparated) return separatedAmount(); if (_isRetired) return retiredAmount(); return normalPayAmount(); ;,Split Loop - 1,void

8、printValues() double averageAge = 0; double totalSalary = 0; for (int i = 0; i people.length; i+) averageAge += peoplei.age; totalSalary += peoplei.salary; averageAge = averageAge / people.length; System.out.println(averageAge); System.out.println(totalSalary); ,void printValues() double totalSalary

9、 = 0; for (int i = 0; i people.length; i+) totalSalary += peoplei.salary; double averageAge = 0; for (int i = 0; i people.length; i+) averageAge += peoplei.age; averageAge = averageAge / people.length; System.out.println(averageAge); System.out.println(totalSalary); ,Split Loop - 2,void printValues(

10、) System.out.println(averageAge(); System.out.println(totalSalary(); private double averageAge() double result = 0; for (int i = 0; i people.length; i+) result += peoplei.age; return result / people.length; private double totalSalary() double result = 0; for (int i = 0; i people.length; i+) result +

11、= peoplei.salary; return result; ,简化条件表达式,分解表达式,if(date.before(SUMMER_START) | date.after(SUMMER_END) charge = quantity * _winterRate + _winterServiceCharge; else charge = quantity * _summerRate,if(notSummer(date) charge = winterCharge(quantity); else charge = summerCharge(quantity);,Remove Double Negative,if ( !item.isNotFound() ) if ( item.isFound() ),在对象之间搬移特性,搬移函数（Move Method) 搬移值域(Move Field) 提炼类(Extract Class) 将类内联化(Inline Class) 隐藏委托关系(Hide Delegate) 移除中间人(Remove Middle Man) 引入外加函数(Introduce Foreign Met